Reforming process



- characteristics.

Patented Aug. 16, 1949 UNITED STATES PATENT OFFICE" 2,478,918 I I nrromvmzq rnocass Vladimir 'Haensel, Clarendon Hills,-and um. F. Gerald, Riverside, Ill., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing.

The saturated gasoline fraction to be treated in accordance with the present invention comprise straight run gasolines, natural gasolines, etc. The gasoline fraction may be a full boiling range gasoline having an initial boiling Application December 21, 1948, Serial No. 717,659

point within the range of about 50 to about 90 F. and an, end boiling point within the range of about 375 to about 425 F., or it may be a selected fraction thereof which usually will be a higher boiling fraction, commonly referred to as naphtha, and generally having an initial boiling point of from about 150 to about 250 F. and en end boiling point within the range of about 350 to about 425 F.

The term reforming is well known in the petroleum industry and refers to the treatment of gasoline fractions to improve the anti-knock characteristics. Straight run gasolines contain naphthenic hydrocarbons, particularly cyclohexane compounds, and paraflinic hydrocarbons which usually are of straight chain or slightly branched chain structure, as well as varying proportions of aromatic hydrocarbons. In order to obtain best results in reforming operations it is desired to dehydrogenate the naphthenic hydrocarbons to produce aromatics, to cyclisize the straight chain paraflinic hydrocarbons to form aromatics, as well as to efiect a controlled type of cracking which is selective both in quality and in quantity. In addition various other concomitant reactions occur such as isomerization, hydrogen transfer, etc.

The cracking or splitting of carbon to carbon bonds is one of the important factors in successful reforming process. Controlled or selective cracking is highly desirable since such cracking will result in a product of improved antiknock In general, the lower molecular weight products have higher octane numbers, and thus a final gasoline product of lower average molecular weight will usually have a higher octane rating. Further, during the mally liquid hydrocarbons substantially or completely into normally gaseous hydrocarbons. The desired selective cracking generally comprises the removal of methyl, ethyl and, to a lesser extent, propyl groups, in the form of methane, ethane and propane as will be herein-- after described. However, the removal of these radicals is controlled so that not more than one or possibly two of such radicals are removed from a given molecule. For example, heptane may be reduced to hexane, nonane to octane or heptane, etc. On the other hand uncontrolled or non-selective cracking will result in the decracking reaction, isomerization or other moleccomposition of normally liquid hydrocarbons into normally gaseous hydrocarbons as, for example, by the continued demethylation of normal heptane to produce '7 molecules of methane.

Another important objection to the non-selective or uncontrolled cracking is that this type of cracking will result in the more rapid formation of larger quantities of coke or carbonaceous material which deposits on the catalyst and decreases or destroys its activity to catalyze the desired reactions. This in turn results in shorter processing cycles or periods, with the necessity of more frequent regeneration of the catalyst by burning'the carbonaceous products therefrom or, should the catalyst activity be destroyed, it will be necessary to shut down the unit to remove the old catalyst and replace it will new catalyst.

Another important feature in successful reforming processes is the matter of hydrogen productionand consumption. Investigation has shown that the'presence of hydrogen in the reforming zone further tends to decrease the amount of carbonaceous deposits on the catalyst. Reforming processes effected in the presence of hydrogen are known as Hydroforming.

In view of the fact that the cost of hydrogen is quite high, it is essential that there be no net consumption of hydrogen or, in other words, at least as much hydrogen must be produced in the process as is consumed therein.

In a broad aspect the present invention relates to a process for reforming a straight run gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst prepared by compositing from about 0.2 gram to about 2 grams per cubic centimeters of final catalyst of a metal selected from the group consisting of platinum and palladium with a dry cracking component.

In a specific embodiment the present invention relates to a process for reforming a straight run gasoline fraction which comprises subjecting said gasoline fraction to contact at a temperature of from about 500 to about 875 F., and a pressure of from about atmospheric to about 1000 pounds per square inch, at on hourly liquid space velocity of from about 0.1 to about 5, in the presence of from about 0.5 to about mols of hydrogen, with a catalyst prepared by compositing from about 0.2 gram to about 2 grams of platinum per 100 cubic centimeters of a dry silica-alumina composite.

.The catalyst used in the present invention comprises platinum or palladium in amounts of from about 0.2 gram to about 2 grams per 100 cubic centimeters of the final catalyst. Concentrations of these metals below about 0.2 gram per 100 cc. are too low for satisfactory reforming operations while, on the other hand, concentrations of platinum above about 2 grams per 100 cc. are unsatfisfactory because they produce excessive cracking. Therefore, it.is an essential feature of the present invention that the concentrations of platinum or palladium in the catalyst shall be within the range of about 0.2

gram to about 2 grams per 100 cubic centimeters of the final catalyst.

. Due to the high cost of platinum and palladium, a major factor in the use of catalysts containing these metals is the quantity thereof to be used. As will be noted, the improved process of the present invention requires small quantities of these metals. However, as the densities of the different cracking components vary considerably, the quantity of platinum or palladium in the present specification and claims has been specified on the basis of grams thereof per cubic centimeters of final catalyst. The final catalyst charged to the process is usually determined asv so much volume required to fill a given portion of the reaction zone, and the present method of specifying the platinum or palladium concentration readily shows the quantity of these metals required.

As another feature of the present invention, we have found that the component to be composited with the platinum or palladium must have substantial activity to catalyze the cracking retion of the salt as the case may permit. The

' the form of granules of irregular size and shape or the ground granules may be formed into pellets of uniform size and shape by pilling, extrusion or other suitable methods.

A particularly satisfactory method of forming the cracking component is to add the acid to commercial water glass at a pH controlled to form silica hydrogel, discharging the mixture of acid and water glass from a rotating disc or nozzle into a bath of oil of sufficient depth so that the action. As hereinbefore set forth, the reforming v the platinum or palladium may comprise any suitable cracking catalyst, either naturally occurring or synthetically produced. Naturally occurring cracking catalysts include various aluminum silicates, particularly when acid treated to increase the activity, such as Super Filtrol, etc. synthetically produced cracking catalysts include silica-alumina, silica-zirconia, silica-aluminazirconia, silica-magnesia, silica-alumina-magnesia, silica-alumina-thoria, alumina-boria, etc. These catalysts may be made in any suitable manner including separate, successive or coprecipitation methods of manufacture. Preferred cracking catalysts comprise silica-alumina or silica-alumina-zirconia which are preferably manufactured by commingling an acid, such as hydrochloric acid, sulfuric acid, etc., with commercial water glass under conditions to precipitate silica, washing with acldulated water or otherwise to remove sodium ions, commingling with an aluminum salt such as aluminum chlosilica hydrogel sets into firm spheres during passage through the oil bath. The spheres maybe removed from the bath in any suitable manner, such as by being transported in a stream of .water disposed beneath the oil layer. The silica spheres may then be treated in any suitable manner to remove sodium ions, followed by impregnating with a solution of soluble metal salt or salts. In another embodiment silica-alumina spheres, silica-magnesia spheres, etc., may be formed by co-precipitation methods in a similar system.

As another essential feature of the present invention it has been found that the cracking component must be dried at a temperature of at least 350 F. before the platinum is composited therewith. This will be shown in detail in the following example, from which it will be noted that catalysts prepared by compositing platinum with dry silica-alumina yield products of high octane number, whereas catalysts prepared by compositing platinum with undried silica-alumina result in products having a much lower octane number. The cracking component may be dried at a temperature of from about 350 to about 500 F., and/or calcined at a temperature of from about 500 to about 1400 F. or more prior to admixing the platinum or palladium therewith. This unexpected result is peculiar to composites of platinum with cracking components and does not occur for composites of platinum with inert supports..

As another important feature of the present invention the temperature to be employed will be within the range of from about 500 to about 875 F. Temperatures below 500 F. are too low for satisfactory conversions. Hydrocracking reactions are favored at temperatures within the range of from about 500 to about 625 F. and at pressures within the range of from about 600 to about 1000 pounds or more. Hydrocracking is defined as cracking or splitting'of carbon to carbon bonds accompanied by saturation of the fragments so formed by hydrogen present in the reaction zone and, in accordance with the present invention, the hydrocracking will be selected both in quality and in quantity as hereinbefore set forth. Onthe other hand the aromatization reactions are favored at temperatures within the range of about 600 to ride, aluminum sulfate, aluminum nitrate, and/or zirconium salt, etc., and either adding a basic precipitant, such as ammonium hydroxide, to precipitate alumina and/or zirconia, or forming the desired oxide or oxides by thermal decomposiabout 875 F., at lower pressures within the range of from atmospheric to about 400 pounds per square inch. It is an essential feature of the present invention that the temperature and pressure be correlated to produce the desired aromatization and selected hydrocracking. The exact temperature and pressure to be used in any given operation will depend upon the particular gasoline being treated, and also will be correlated with the hourly liquid space velocity. Hourly liquid space velocities (defined as the volume of liquid hydrocarbon oil per hour per volume-of catalyst) will be within the range of from about 0.1 to about 5.

In one manner of operation of the process, sufficient hydrogen will be produced in the reforming reaction to saturate the hydrocarbon fragments formed therein and, therefore, it may be unnecessary to either introduce hydrogen from an extraneous source or to recycle hydrogen within the process. However, it usually will be preferred to either introduce hydrogen from an extraneous source, generally at the beginning of th operation, and to recycle hydrogen within the process in order to assure a suflicient hydrogen atmosphere in the reaction zone. Hydrogen serves to reduce carbon formation and thereby to lengthen the life of the catalyst.

The composite catalyst of the present invention may be prepared in any suitable manner, a preferred method comprising admixing chloroplatinic acid or chloropalladium acid in the desired amounts with the cracking component which had previously been dried and/or calcined in the manner hereinbefore set forth. The composite of platinum or, palladium chloride and cracking component is then dried and treated with hydrogen to reduce the chloride to the metal. It is understood that other suitable methods of preparing the catalyst may be employed, but that the amount of platinum or palladium solution utilized is controlled so that the final catalyst contains from about 0.2 gram to about 2 grams per 100 cubic centimeters thereof.

After a period of service, it will be necessary to reactivate the catalyst and this may readily be accomplished by passing air or other oxygencontaining gases therethrough in order to burn carbonaceous deposits from the catalyst. A particularly. suitable manner of regenerating the catalyst comprises effecting the regeneration at a temperature of about 900 to about 950 F., starting with a gas containing about 2% oxygen and gradually increasing the oxygen concentration so that at the end of the regeneration period pure air is being passed over the catalyst. However, it is important that the temperature of regeneration should not exceed 1000 F. as'it has been found that these high temperatures tend to impair the catalyst activity. It should be made clear that the use of temperatures above 1000 F. is not harmful when applied to the cracking component before the platinum or palladium is composited therewith, but that after the coinponents have been composited, the final composite should not be subjected to temperatures above 1000 '35. either during regeneration or during preparation of the catalyst. v

The platinum and palladium-containing catalysts appear .to be adversely affected by sulfur and it is therefore, generally preferred that the charging stock to the reforming process be substantially sulfur-free. In another embodiment of the invention, straight run gasoline contain ing sulfur compounds may be subjected to desulfurization in any suitable manner and the desulfurized gasoline may then be subjected to reforming treatment in the manner hereinbefore set forth. Any suitable desulfurizing catalyst may be employed such as the oxides and/or sulfides of nickel, molybdenum, chromium, etc., or various clays and synthetic silica-alumina composites, etc. A particularly suitable catalyst for use in the desulfurization step of the combination process comprises silica-alumina-nlckel which is preferably employed at a temperature of from about 400 to about 750? F. and at a superatmospheric pressure of from about 50 to about 1000 pounds per square inch.

The process of th present invention may be effected-in any suitable equipment. A particularly suitable process comprises the well known fixed bed system in which the catalyst is disposed in a reaction zone and the gasoline is passed therethrough at the proper conditions of operation in either upward or downward flow. The

products are fractionated to separate excess hydrogen and to recover the desired gasoline fraction. As hereinbefore set forth the hydrogen may be recycled for further use in the process. Other suitable units in which the process may be effected include the fluidized type process in which the hydrocarbon and catalyst are maintained in a state of turbulence under hindered settling conditions in the. reaction zone, the compact moving bed type process in which the catalyst and hydrocarbon are passed either concurrently or countercurrently to each other, and the suspensoid type operation in which the catalyst is carried as a slurry in the hydrocarbon oil into the reaction zone.

The following examples are introduced to further illustrate the novelty and utility of the present invention but not with the intention of undruly limiting the same.

' EXAMPLE I which ammonium hydroxide was added to precipitate alumina. The silica-alumina-zirconia composite was partially dried, formed into pills in a pelleting machine, and then calcined. So-

, lutions of chloroplatinic acid of the desired concentrations were added to different samples of the silica-alumina-zirconia composite and subsequently the impregnated composite was treated with a hydrogen-containing gas at a temperature increasing from about 295 F to about 573 F. in order to reduce the platinic chloride to platinum.

The reforming operation was directed at a temperature of about 695 'F., a pressure of 50 1 pounds per square inch, an hourly liquid space velocity of 0.5 and a hydrogen to hydrocarbon ratio of 2.7:1. The results of these runs are shown in the following table.

Table I Run No Charge 1 2 3 4 5 Platinum, grams per cc. offlnalcatalyst. 0.35 0. 7 1.0 1.5 2.1 Liquid recovery, percent by volume 93.2 91.9 93.4 92.8 93.2 Octane No.:

Motor Method, I

Clear 32.7 64.3 64.3 66.3 66.1 66.3 Motor Method+ 3 cc. TEL 61. 3 77. 7 79. 0 79.1 80. 2 80. 0 5 crcent boiling point y Eneler distillation- 257 214 208 118 192 202 Hydrogen produced, cubic it. per barrel of charge 630 801 802 783 897 It will be noted that the octane number of the naphtha was increased from 32.7 to above 64 clear and from 61.3 to above 77 upon the addi- EXAMPLE II The Mid-Continent naphtha used in Example I was subjected toreforming in the presence of catalysts containing varying percentages of platinum and composited with difierent cracking components. The reforming was effected at a temperature of about 775 F., a pressure of 200 pounds per square inch, an hourly liquid space velocity of 0.5 and a hydrogen to hydrocarbon ratio of 2.7:1.

The silica-alumina-zirconia component was prepared in the manner described in Example I. The silica-alumina component was prepared by adding hydrochloric acid to commercial water glass in proportions to precipitate silica hydrogel, the silica hydrogel being formed into spheres by discharging the mixture of water glass and acid into an oil bath in the manner hereinbefore set forth. The silica spheres were washed with acidulated water to remove sodium ions and the spheres were then submerged in a bath of aluminum chloride, after which anmionium hydroxide was added to precipitate alumina. The silicaal-umina composite was then dried at a temperature of about 250 F. for ten hours and then calcined at a temperature of 932 F. for about 1 hours.

Solutions of chloroplatinic acid of the desired concentrations were added to different samples 8 paraflins. It likewise will be noted thatwith the platinum-silica-alumina catalysts, the percentage of non-condensible parafllns increases from 2% to about 5% when the platinum concentration is increased from less than 2 grams (run 8) to more than 2 grams per 100 cc. (run 9), The

increased cracking and resultant carbon formation and gas production are undesirable because of the carbon depositing on and therefore deactivating the catalyst, and because hydrogen is consumed in saturating the fragments formed by cracking and also because there is a loss of valuable gasoline components to less valuable gases.

In all cases a will be noted that the yields of liquid product decreases and the octane numbers of the gasoline decreases as the. platinum concentration is increased above 2. grams per 100 cc. of final catalyst.

- special attention is calledto the fact that, in run No. 6, a yield of 90.4% by volume of gasoline having as clear octane number of 82.5 was obtained. Special attention also is called to run 8, in which there was produced 97.4% of gasoline having a clear octane number of 77.4 and of 88.2 with 3 cc. of T. E. L. These results are better than heretofore obtained in any reforming process. It will be recalled that most reforming processes are directed to obtaining an 80% yield of an 80 octane number product. It is thus readily seen that the process of the present invention produces greatly improved results.

Emu: III

As hereinbefore set forth, the component composited with the platinum or palladium must have cracking activity. This is illustrated in the following table which shows the results of treating a Mid-Continent naphtha at atemperature of about 693 F.. a pressure of pounds per square inch, an hourly liquid space velocity of Table I" It will be noted that the platinum-silica-alumina-zirconia catalyst containing less than 2 containing over 2 grams of platinum per 100 cc.

(run 7) produced about 18% Run No. 11 12 1a 14 us 10 Catalyst Carrier Silica-alumina... Built-32mins- Silica-zirconis... Bilicamagnesisn Silica... Alumina. Liquid yield, volume 91.5 92. 3 02.4-; 02.2 '94s"... on.

percent of charge. Octane Nos. Motor 71.2 d6.l 65.3 62.6.. 58.0..- 61.5.

Method Clear. Motor Method+3 ec. 81.8 aoa 10.4 15s 142.-." 11.0. TEL. v of the cracking components and the final cat- 0.5 and a hydrogen to hydrocarbon ratio of 2.5:1. alysts were prepared in the manner described 'I'heMid-Continent naphtha hadanoctane numin Example I. The results of these runs are ber of 40 clear and of 65.6 with 3 cc. of tetraethyl indicatedin the following table. lead by the motor method.

Table n It will be noted that platinum catalysts composited with cracking components (runs 11 to 14) produced gasolines of clear octane number above 6 7 8 9 so, whereas the use of inert catalyst carriers 50 (runs 15 and 18) yielded gasolines of clear oc- Ei'li'ittdttltttdiffffa thma sailfish? time numbers below 00 a zilgiigfiliifiiftfffi- 90.4 as? 91.4 94.0 can I N c fitmhahod, Clearsat 70.5 71.4 90.4 us As er in for forth it 8 m flllt m g gi 3 86 7 a 89 o 8 cracking component be dried before it is com- Percent nth'bh'iisibi posited with the platinum or palladium. This is Imam exit illustrated by the results shown in the following table. The Mid-Continent naphtha used in Example was subjected to reforming with platinum-silica-alumina catalysts prepared by compositing the platinum with silica-alumina which non-condensible 76 undried silica-alumina.

Table 17 Run N Charge 17 i 18 19 Catalyst Preparation Silica-alumina dried at Undried... Undrlod.

250 F. and calcined at 932 F. Reforming temperature, F 698..... 075 885 Hydrogen to Hydrocarbon Ratio 2. 65 2.7 2. 57 Hydrogen produced, cubic It. per barrel of charge 725.-. 76 Octane No., Motor Method, clear 32. 7... 71.2 43.o 50.5

It will be noted that the catalysts prepared by compositing platinum with undried silica-alumina gave low octane number products even at a temperature of 885 F., while thecatalyst prepared by compositing'platinum with dry silicaalumina gave a much higher octane number product.

We claim as our invention:

1. A process for reforming a gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst consisting essentially of a cracking component and a metal from the group consisting of platinum and palladium, said cracking component comprising silica and at least one metal oxide from the group consisting of alumina, zirconia, magnesia and thoria, and said metal being present in an amount of from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst.

2. A process for reforming a saturated gasoline fraction which comprises subjecting said fraction to contact at a temperature within the range of from about 500 to about 875 F., a pressure of from atmospheric to about 1000 pounds per square 'inch, and an hourly liquid space .velocity of from about 0.1 to 5, in the presence of from about 0.5 to about mols of hydrogen per mol of hydrocarbon, with a catalyst prepared by compositing from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst of a metal selected from the group consisting of platinum and palladium with a dry cracking component comprising silica and alumina.

3. A process for reforming a straight run gasoline fraction which comprises subjecting said fraction to contact at a temperature of from about 500 to about 875 F., a pressure of from atmospheric to about 1000 pounds per square inch, and an hourly liquid space velocity of from about 0.1 to 5, in the presence'of from about 0.5 to about 10 mols of hydrogen per mol of hydro-' carbon, with a catalyst prepared by compositing from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst of platinum with a dry cracking catalyst comprising silica and alumina.

4. The process of claim 3 further characterized in that said cracking catalyst also contains zirconia.

5. A process for reforming a straight run gasoline fraction which comprises subjecting said fraction to contact at a temperature of from about500 to about 875 F., a. pressure of from atmospheric to about 1000 pounds per square inch, and an hourly liquid space velocity of from about 0.1 to 5, in the presence of from about 0.5 to about 10 mols of hydrogen per mol of hydrocarbon, with a catalyst prepared by compositing from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst of platinum with a dry cracking catalyst comprising silica and zirconia.

6. A process for'reforming a straight run gasoline fraction which comprises subjecting said fraction to contact at atemperature of from about 500 to about 875 F.,'a pressure of from atmospheric to .about 1000 pounds per square inch, and an hourly liquid'space velocity of from about 0.1 to 5, in the presence of from about 0.5

'to about 10 mols of hydrogen'per mol-of hydrocarbon, with a catalyst prepared by compositing from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst of platinum with a dry silica-magnesia cracking catalyst.

7. A process which comprises subjecting a sulfur-containing gasoline fraction to a desulfurization treatment and thensubjecting the desulfurized gasoline fraction to reforming in the presence of a platinum-silica-alumina catalyst containing from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst of platinum, said catalyst having been prepared by compositing the platinum withdried silica-alumina.

8. A process for reforming a gasoline fraction which comprises subjecting said'fraction to contact at reforming conditions with a catalyst consistin essentially of a cracking component and a,v metal from the group consisting of platinum and palladium, said cracking component comprising silica and alumina and said metal beingpresent in an amount of from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst.

9.The process as defined in claim 8-further characterized in that said cracking component comprises zirconia in addition to the silica and alumina.

and palladium, said cracking component comprising silica andzlrconia and said metal being present in an amount of from about 0.2 gram to about 2 rams per 100 cubic centimeters of final catalyst. 11. A process for reforming a gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst consisting essentially of a cracking component and a metal from the group consisting of platinum and palladium, said cracking component comprising silica and magnesia and said metal being present in an amount of from about 0.2 gram to about2 grams per 100 cubic centimeters of final catalyst. I

which comprises subjecting said fraction to con- 4 tact at reforming conditions with a catalyst preplatinum and palladium in an amount of from about 0.2 gram to about 2 grams per cubic centimeters of final catalyst.

13. A process for reforming a saturated gasoline. fraction which comprises subjecting said fraction to contact at a temperature within the I range of from about 500 to about 875 l"., a pressure of from atmospheric to about 1000 pounds per square inch, and an hourly liquid space velocity of from about 0.1 to 5, in the presence of from about 0.5 to about 10 mols of hydrogen per mol oi lrvdrocarbon,,with a catalyst prepared bydrying a composite comprising silica. hydrogel and alumina hydrogel at a temperature 01' at least 350 1''. and incorporating into the dried composite a metal from the group consisting of platinum and palladium in an amountot from about 0.2 gram to about 2 grams per 100 cubic centimeters of final catalyst.

VLADIMIR- HAENSEL. CURTIS I. GERALD.

REFERENCES CITED The following references are of record in the file oi this patent:

Marisic Oct. '1, 194'! "Catalytic Reforming of Straight Run Gasoline Increases Aromatic Content, Komarewsky et al., The Oil and Gas Journal, June 24, 1943, mes 90 to 93 and 119.

"Aromatization by Catalysis of Fractions oi. Bakou Gasoline," Zelinsky et al., Industrial and Engineering Chem., vol. 27, No. 10, October 1985 (pages 1209. 1210. 1211).

Neitvanse Khozyaisto (Russian), vol. 26, N0 3,

mes42to44 (m4). 

